A microphone comprises an acoustic-to-electric transducer or sensor that converts sound into an electric signal. Condenser microphones, also known as capacitor microphones, comprise a diaphragm that acts as one plate of a capacitor and vibrates in response to incoming acoustic signals, or sound pressure, whereby the vibrations produce changes in the distance between the plates and, as a result, the capacitance. According to the equation Q=CV for a capacitor, a change of capacitance, C, may result in a change in voltage, V, if the charge, Q, of the capacitor is kept constant. In this way, an acoustic signal (pressure wave) may be converted to a change of capacitance via the deflection of the diaphragm, which may be converted into an electrical signal which can be amplified or recorded.
In cellular telephones it may be desirable to have a microphone with a frequency response that corresponds to the frequency content of a human speaker's voice, e.g., a frequency response of about 300-3000 Hz, meaning that the microphone may amplify or record frequencies within that range.
In some environments, such as an outdoor environment, sound quality may, however, be adversely affected by background noise, such as by wind that blows into the microphone. Wind noise may increase the low frequency component of the acoustic signal entering the microphone; it can easily overwhelm the voice of a human speaker using the cellular telephone and saturate the microphone's amplifier.